Evaluation of the GORE® TBE Device in the Treatment of Lesions of the Aortic Arch and Descending Thoracic Aorta, Zone 0/1: Complete Statistical Analysis

1. Trial at a Glance

This page covers the registry results for Evaluation of the GORE® TBE Device in the Treatment of Lesions of the Aortic Arch and Descending Thoracic Aorta, Zone 0/1 (NCT02777528), a non-randomized na study. The primary outcome is Proportion of Participants With Primary Endpoint Success Through 1 Month for Zone 0/1.

2. Clinical Question

The question concerns endpoint success after a procedure for aortic lesions. The endpoint combines procedural and device-related criteria with the absence of specified serious events. It is therefore broader than a measure of device technical performance alone: a participant must meet the composite definition, rather than only one component, to count as a success under that definition.

The registry record does not report the primary endpoint numerator, denominator, or estimate. It consequently does not establish from the posted outcome information what proportion met the composite definition or how precisely that proportion was estimated. The listed objective is to assess safety and effectiveness, but the numerical primary result is not reported in the registry record.

3. Trial Design

This is a nonrandomized, single-group device study with no masking listed. The registry lists the phase as NA and enrollment as 79. The sponsor is W.L.Gore & Associates. The record gives a start of 2016-08, a primary completion of 2024-03, and a status of active, not recruiting.

The intervention listing includes the GORE® TAG® Thoracic Branch Endoprosthesis and a revascularization procedure. The registry separates participants into a Zone 0/1 Aortic aneurysm cohort, a Zone 0/1 Dissection cohort, and a Zone 0/1 Other Isolated Lesion cohort; the last description includes dissection and other isolated lesion types, while the separate dissection cohort is also listed. These cohort labels describe lesion groups, not randomized treatment assignments.

Because no randomized control group is listed, the study does not provide a randomized comparison of the device strategy against an alternative. Differences between its lesion cohorts, if considered, would not by themselves isolate a treatment effect: cohort membership is not randomized, and the groups are not described as a like-for-like control comparison.

The registry record does not report a detailed statistical plan, a sample-size justification, or the basis for the enrollment target. It also does not report whether interim analyses were planned or performed. Planning calculations are not a substitute for those design details and should not be read as the trial’s original design rationale.

4. Participant Flow and Accounting

The registry reports how participants moved through each stage of the study. All counts below are exactly as posted; missing counts are not inferred from other stages.

Before assignment: The study enrolled participants into 2 Zones (7 total cohorts) and results are reported by zone. This record (NCT02777528) contains the results for the 3 cohorts of Zone 0/1 (Zone 0/1 Aneurysm Cohort, Zone 0/1 Dissection Cohort, Zone 0/1 Other Isolated Lesion Cohort). Results for the 4 cohorts of Zone 2 (Zone 2 Aneurysm Cohort, Zone 2 Dissection Cohort, Zone 2 Other Lesions Cohort, Zone 2 Traumatic Transection Cohort) are reported in a separate record (NCT02777593).

Overall Study

Reasons for not completing this period:

Analysis population for the primary outcome, as defined in the registry: Two Zone 0/1 Aneurysm participants that are counted in the Participant Flow section above are excluded from this analysis, as pre-specified due to treatment with 49/53 mm devices no longer supported by the protocol. Primary Endpoint composite denominator was restricted to number of participants either with a primary endpoint event or imaging performed in the 1 Month window.

5. Baseline Characteristics

The table reproduces the baseline characteristics posted in the registry, which describe the participants analysed at baseline and help show whether the randomized groups were comparable.

Population: Two Zone 0/1 Aneurysm participants that are counted in the Participant Flow section above are excluded from this analysis, as pre-specified, due to treatment with 49/53 mm device no longer supported by the protocol. As described in the Participant Flow Section, the study reports results in 2 separate records. Zone 2 cohorts are reported in record NCT02777593.

6. Primary Endpoint

The registry lists the primary outcome as Proportion of Participants With Primary Endpoint Success Through 1 Month for Zone 0/1, measured over 1 month.

The primary endpoint is the proportion of participants with primary endpoint success through 1 month for Zone 0/1. It is a composite: it includes initiation of the index endovascular procedure following the debranching procedure, device technical success for the index endovascular procedure, and absence of specified complications or additional procedures. Those specified events include aortic rupture, lesion-related mortality, disabling stroke, permanent paraplegia, permanent paraparesis, new-onset renal failure requiring permanent dialysis, and an additional unanticipated post-procedural surgical or interventional procedure related to the device, procedure, or withdrawal of the delivery system.

The general purpose of a composite endpoint is to represent a set of clinically relevant outcomes in a single measure. It can capture more than technical success alone, but it also means that the overall result depends on the full definition and on how often its individual components occur. A participant’s status under the composite does not reveal which component drove the classification unless component results are reported separately.

The timeframe is through 1 month following the endovascular procedure, through day 59 unless otherwise specified. The description limits disabling stroke, permanent paraplegia, permanent paraparesis, and new-onset renal failure requiring permanent dialysis to 30 days. The primary endpoint result and its component counts are not reported in the registry record.

7. Why No Re-analysis Is Shown

8. Statistical Interpretation

9. Statistical Methods Explained

What kind of outcome is the primary endpoint?

The endpoint is a binary participant-level outcome summarized as a proportion: participants are classified according to whether they meet the composite success definition. In general, a proportion is the number meeting a defined condition relative to the eligible analysis population. Interpretation depends on both the success count and the denominator, as well as on consistent application of the endpoint criteria. The registry record does not report the primary success count or the complete analysis denominator, so it does not permit a numerical proportion to be interpreted.

A composite endpoint combines multiple events or criteria. This approach can give a single summary of several aspects of procedural and clinical outcome. However, the components may differ in seriousness and frequency, so the composite alone can conceal which component contributes most to the overall classification. Component-level results can clarify that pattern, but component counts for the primary endpoint are not reported in the registry record.

How should uncertainty be understood?

In general, a confidence interval describes the range of estimates compatible with the observed data under a statistical procedure and its assumptions. A narrow interval indicates greater precision than a wide interval; neither establishes that an estimate is free of bias. For a proportion, precision depends on the number of observations and on the observed event frequency. The registry record does not report a primary endpoint estimate or confidence interval, so precision for the primary outcome cannot be evaluated from the record.

Uncertainty is also different from design bias. A confidence interval quantifies sampling uncertainty under its method, but it does not correct for selection effects, outcome misclassification, missing data, or confounding. This distinction is especially relevant to a nonrandomized, single-group study: statistical precision around an observed proportion would not create a randomized comparison or establish a causal effect.

What do the planning calculations mean?

The planning illustrations use a two-sided significance level of 0.05, equal allocation between two arms, and a normal approximation. They frame the effect to detect as a stated fraction of the observed effect. For time-to-event calculations, the stated quantity is total events using the Schoenfeld approach; other calculations are expressed as participants per arm. These are planning illustrations, not observed power, and they do not establish the design choices made for this single-group trial. The registry record does not report a sample-size justification or its statistical design rationale.

Planning calculations depend on assumptions about the effect to detect and the design being considered. An illustration based on an observed effect is not proof that a future study has adequate power, and it does not describe the precision of the current study’s primary endpoint. The underlying observed primary effect is not reported in the registry record, so the calculations should not be read as a substitute for that result.

How does the design affect interpretation?

Random allocation, when used, can help balance measured and unmeasured participant characteristics across assigned groups. This study is listed as nonrandomized and single-group, and no concurrent comparator is listed. The observed outcomes can therefore describe the enrolled and analyzed participants, but comparisons with an external benchmark or with a different cohort would require additional assumptions. Such assumptions and any adjusted comparative analysis are not reported in the registry record.

The endpoint’s time window is also part of its statistical definition. It extends through 1 month after the endovascular procedure, through day 59 unless otherwise specified, while certain neurologic and renal events are limited to 30 days. Different windows can affect which events qualify for the composite. The record defines those windows but does not provide participant-level follow-up completeness or endpoint counts.

Overall, the statistical framework that can be described is limited to a binary composite outcome in a single-group study, with planning illustrations using stated assumptions. The registry record does not report enough primary outcome information to assess the observed proportion, its confidence interval, component contribution, or analysis precision.

10. Exact Estimates for Each Arm

No two-arm comparison is shown for this trial, but each arm's result can still be summarized with exact interval estimates computed from the posted counts. The Clopper-Pearson interval is exact and conservative; the Wilson interval is a common closer-to-nominal alternative; the Bayesian credible interval uses a uniform Beta(1, 1) prior. For small groups the three can differ noticeably.

R code and output

arm    <- c("Zone 0/1 Aneurysm Cohort", "Zone 0/1 Dissection Cohort", "Zone 0/1 Other Isolated Lesion Cohort")
n      <- c(47, 22, 3)
events <- c(0, 0, 0)
for (i in seq_along(n)) {
  ci <- binom.test(events[i], n[i])$conf.int          # Clopper-Pearson exact interval
  cr <- qbeta(c(0.025, 0.975), 1 + events[i], 1 + n[i] - events[i])   # Bayesian, uniform Beta(1,1) prior
  wi <- (function(x, n) { p <- x / n; z <- qnorm(0.975); d <- 1 + z^2 / n
    c((p + z^2 / (2 * n) - z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d, (p + z^2 / (2 * n) + z * sqrt(p * (1 - p) / n + z^2 / (4 * n^2))) / d) })(events[i], n[i])
  cat(sprintf("ARM|%s|%d|%d|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f|%.1f\n", arm[i], n[i], events[i], 100 * events[i] / n[i],
              100 * ci[1], 100 * ci[2], 100 * wi[1], 100 * wi[2], 100 * cr[1], 100 * cr[2]))
}

ARM  Zone 0/1 Aneurysm Cohort  47  0  0.0  0.0  7.5  0.0  7.6  0.1  7.4
ARM  Zone 0/1 Dissection Cohort  22  0  0.0  0.0  15.4  -0.0  14.9  0.1  14.8
ARM  Zone 0/1 Other Isolated Lesion Cohort  3  0  0.0  0.0  70.8  0.0  56.1  0.6  60.2

11. Multiplicity, Missing Data and Analysis Populations

The registry lists two outcome measures, but the primary endpoint described in the record is the proportion with composite success through 1 month. Details of the other outcome measure are not reported in the registry record. A multiplicity adjustment, hierarchy for testing outcomes, or other strategy for controlling the chance of false-positive findings is not reported in the registry record. It would not be appropriate to infer a testing strategy from the count of listed outcomes alone.

The primary analysis population is not fully described in the available endpoint text. The record states that two Zone 0/1 Aneurysm participants counted in Participant Flow are excluded from this analysis because they were treated with 49/53 mm devices no longer supported by the protocol, as prespecified. It also says that the primary endpoint composite denominator was restricted, but the full eligibility wording for that denominator is not reported in the registry record. The complete denominator and primary success count are not reported.

Rules for missing endpoint data, incomplete follow-up, withdrawals, and handling of participants whose endpoint status cannot be determined are not reported in the registry record. The record also does not report whether sensitivity analyses were used to assess the effects of missing data. These details matter because the estimated proportion may depend on which participants are included and how unresolved outcomes are classified.

The record does not provide enough information to determine whether the listed analysis used an intention-to-treat, per-protocol, or another analysis population, beyond the stated exclusions and denominator restriction. The prespecified device-related exclusion is explicit, but it does not fill in the missing denominator rules or explain the treatment of other potential analysis issues.

12. Safety Results

The registry reports serious adverse events as affected participants divided by participants at risk.

Deaths

Other (non-serious) adverse events

Participants with at least one non-serious event at or above the registry's 5% reporting threshold.

Most frequent serious adverse event terms

Most frequent non-serious adverse event terms

Serious events with the highest arm-level rate: vision loss (33.3%), unknown cause of death (33.3%), acute hypoxic respiratory failure (9.6%), chronic obstructive pulmonary disease exacerbation (9.6%), atrial fibrillation with rapid ventricular response (8.3%).

The safety record lists participants at risk and participants affected for serious and other adverse events separately within each cohort. In the Zone 0/1 Aneurysm Cohort, the serious-event figures are 52 at risk and 43 affected; the other-event figures are 52 at risk and 40 affected, with 14 deaths listed. In the Zone 0/1 Dissection Cohort, the corresponding figures are 24 and 19 for serious events, 24 and 21 for other events, and 7 deaths. In the Zone 0/1 Other Isolated Lesion Cohort, they are 3 and 1 for serious events, 3 and 2 for other events, and 1 death.

These are cohort-specific counts. They should not be added together or treated as a comparison of treatment groups. The record does not give the event attribution, follow-up duration for these summaries, or full rules for counting recurrent events. The death counts are listed, but the summary does not specify their causes.

Selected serious adverse-event terms include Vision loss and Unknown cause of death, each listed as 33.3%; Acute hypoxic respiratory failure and Chronic obstructive pulmonary disease exacerbation, each as 9.6%; and Atrial fibrillation with rapid ventricular response and Abdominal pain, each as 8.3%. The denominator and calculation rule for these percentages are not reported in the registry record, so they should not be read as cohort-level risks or as evidence of causation.

13. What the Result Does, and Does Not, Mean

The result that can be read from the registry record is the trial’s planned clinical question and its endpoint definition, not a reported primary endpoint finding. The record identifies a composite measure of success through 1 month and describes the procedural and clinical criteria that contribute to it. It does not report the number of participants meeting the definition, the denominator used for the primary estimate, or the resulting proportion.

Without those primary outcome quantities, the posted information cannot establish the observed frequency of success or the precision of an estimate. It also cannot show which composite components most affected the result. The safety counts and selected adverse-event terms provide descriptive information, but do not resolve the missing primary endpoint result.

Even a reported single-group proportion would answer a descriptive question about the participants included in that analysis. It would not alone show what would have happened to comparable participants under an alternative treatment. The nonrandomized, single-group design and absence of a concurrent comparator limit causal interpretation. Comparisons between the lesion cohorts would not replace a randomized control comparison because the cohorts are not described as like-for-like controls.

The registry record also specifies that two Zone 0/1 Aneurysm participants were excluded from the primary analysis because they received 49/53 mm devices no longer supported by the protocol. The full primary denominator rule is not reported in the registry record, so the impact of the complete analysis-population definition cannot be assessed.

Thus, the record supports a description of the study design, endpoint criteria, and selected safety counts. It does not support a numerical conclusion about primary endpoint success, a comparative treatment effect, or a causal claim. Those conclusions require outcome and analysis details that are not reported in the registry record.

14. Why This Trial Matters Statistically

This trial raises several statistical issues common to device studies. The primary outcome is a composite, so its definition determines what counts as success and how the result should be understood. The endpoint combines device technical success and procedural criteria with the absence of specified serious events and additional procedures. A single composite estimate would not show whether its result was driven by technical performance, a particular complication, or another component; component reporting is important for that interpretation.

The study’s single-group, nonrandomized structure also shapes the question it can answer. An observed proportion can describe outcomes in the analyzed participants, but without a concurrent randomized comparator it cannot isolate the effect of the device strategy from other explanations. Lesion cohorts may be clinically distinct and are not a like-for-like control comparison according to the registry record.

Analysis-population rules matter as well. The registry identifies a prespecified exclusion of two Zone 0/1 Aneurysm participants treated with 49/53 mm devices no longer supported by the protocol. It also describes a restricted composite denominator, but the full restriction is not reported. Readers need complete denominator rules to understand exactly which participants contribute to an endpoint proportion.

Finally, the registry record reports safety counts but not the primary endpoint estimate. This contrast illustrates why a well-defined question and detailed event summaries do not substitute for a posted outcome result. Statistical interpretation depends on the observed outcome, its denominator, and measures of uncertainty, not only on the planned endpoint definition. The absence of these primary-result details leaves the principal question unanswered in the registry record.

15. Limitations

• The posted summary statistics are the only data these results rest on; patient-level data, full protocols and statistical analysis plans are not available.
• Recalculated results are simple, unadjusted calculations from posted summaries. They do not replace the sponsor's prespecified analysis.

The principal limitation for interpretation is that the registry record does not report the primary endpoint result. The success numerator, analysis denominator, estimated proportion, and confidence interval are not reported. Component-specific primary endpoint results are also not reported, preventing assessment of which criteria contributed to success or failure.

The analysis population is only partly described. The record identifies the prespecified exclusion of two Zone 0/1 Aneurysm participants treated with 49/53 mm devices no longer supported by the protocol, and notes a restricted composite denominator. The full restriction is not reported in the registry record. Missing-data rules, follow-up completeness, and sensitivity analyses are also not reported, limiting assessment of potential effects from incomplete outcome ascertainment.

The design is nonrandomized and single-group, with no concurrent comparator listed. That limits comparative and causal interpretation. The lesion cohorts should not be treated as equivalent controls. The record does not provide a detailed statistical analysis plan, sample-size justification, interim-analysis information, or a reported approach to multiplicity.

The safety summary has its own interpretive limits. The record lists cohort-specific counts and selected serious-event terms, but the attribution rules, complete event-counting details, and denominators for the listed percentages are not reported in the registry record. These summaries therefore do not establish that an event was caused by the device or procedure, nor do the listed term percentages provide a complete account of safety.

These limitations describe what cannot be determined from the registry record; they do not imply that unreported analyses were not conducted.

16. Related Tutorials

17. Related Statistical Calculators

18. Sources

• ClinicalTrials.gov: Evaluation of the GORE® TBE Device in the Treatment of Lesions of the Aortic Arch and Descending Thoracic Aorta, Zone 0/1 — NCT02777528.
• Registry record last updated 2026-09-10; status last verified 2026-08.
• Results first posted 2025-06-25.
• Data retrieved from ClinicalTrials.gov on 2026-11-09.
• Group sizes, means, event counts and sponsor-reported p-values are reproduced as posted. Effect estimates, confidence intervals and p-values not attributed to the sponsor are independently calculated from the posted summary statistics.

19. Record Summary

The registry record describes NCT02777528, a nonrandomized, non-masked, single-group device study sponsored by W.L.Gore & Associates. Enrollment is listed as 79, phase as NA, and status as active, not recruiting. The record gives a start of 2016-08 and primary completion of 2024-03.

The study evaluates the GORE® TAG® Thoracic Branch Endoprosthesis for Zone 0/1 aortic lesions, with a revascularization procedure also listed. Cohorts include aneurysm, dissection, and other isolated lesion groups. The primary outcome is composite endpoint success through 1 month, with specified procedural, technical, and clinical criteria.

The registry lists cohort-level adverse-event counts and selected serious-event terms. It does not report the primary endpoint result, complete analysis denominator, or confidence interval. A randomized comparator is not listed, and the record does not report a detailed statistical plan or sample-size justification.